The E-M1 is still pretty darn compelling as a body to use the 12-100mm f4. The main issue is the pull on the battery by the dual IS system. One definitely needs to go out for a day's shoot with at least three batteries for safety's sake, but I think the profiles for the camera/lens combination in DXO may be better for the E-M1 and 12-100 vs. the E-M1 Mark II and 12-100. At least, I'm certainly having better results with the E-M1 files in DXO than with the E-M1 Mark II raw files.

12mm..

and from the same spot as the above shot, but zoomed to 100mm, an excellent range to have in one lens..